The Syracuse strains of rats have been selectively bred for either high (SHA) or low (SLA) levels of avoidance responding in two-way shuttlebox. They have been found to differ in a variety of other behavioral, anatomical, and physiological characteristics in addition to the profound difference in avoidance behavior. The genetic architecture of these strains is to be determined by completing an analysis of linkage in F2,BH, and BL populations, by the development of recombinant inbred strains, and by rederivation with a control line from F6 animals. A variety of Pavlovian and operant conditioning procedures will be used to analyze the ways in which the animals of the two strains differ in their affective, attentional and temporal-processing capacities. The role of the hippocampus longterm potentiation and lesions of the hippocampus. The strain difference in preference for oral ethanol will be analyzed by determining the reinforcing or aversive post-ingestional effects of ethanol and by measuring the activity and isozyme patterns of the liver enzymes involved in ethanol and by measuring the activity and isozyme patterns of the liver enzymes involved in ethanol metabolism. The strain differences in the hypothalamic-pituitary-adrenocortical (HPA) axis will be analyzed by experiments on the half-life of corticosterone and by in vitro determinations of the responsitivity of the various levels of the HPA. The experiments make use of these genetic models to increase our understanding of the psychobiological mechanisms underlying individual differences in responsitivity to stress and in how individuals differ in their capacity to cope with stressful situations. Similarly, the experiments will increase our understanding of the genetic and experiential determinants of alcoholism and other psychopathologies.